THE AMERICAN GERIATRICS SOCIETY Geriatrics Health Professionals.

1. GERIATRIC ANESTHESIA:AN INTRODUCTION Jeannette Lee, MDAnesthesiology ResidentRuben J. Azocar, MD Associate Professor of Anesthesiology AGS THE AMERICAN GERIATRICS SOCIETY Geriatrics Health Professionals. Leading change. Improving care for older adults.

2. Objectives • Review the ongoing demographic changes in the elderly segment of the population • Analyze the impact of the growing geriatric populations in health care • Summarize the most important physiologic changes that occur with aging

3. Elderly population • “Elderly” is defined as >65 years old • “Very old” is defined as >85 years old • The elderly population currently comprises 12% of the US population • Projected to increase to 20% by 2040

4. Elderly population in the US

5. Elderly population in the US

6. THE Elderly AS A PROPORTIONOF THE US POPULATION

7. Global Elderly Population • In 2000 the global population >65 years old was estimated to be 420 million • It is projected that by 2010, the elderly population will increase 847,000 per month http://www.census.gov/prod/2001pubs/p95-01-1.pdf

8. Global Elderly Population

9. Procedures for the Elderly • From 19942005 the average number of inpatient procedures per year in patients >65 years old increased from 6,500,000 to 7,353,000 • Currently 35% of all surgical procedures are performed in elderly patients • More than half of the elderly population will have at least one procedure done before they die www.cdc.gov/nchs/data/hus/hus07.pdf#102

10. Postoperative Mortalityin the Elderly • Monk et al reported a prospective observational study of 1064 patients undergoing noncardiac surgery • > 65 yohad a 1-year mortality rate of 10.3% vs. 5.5% in all patients • >65 yo had a relative risk of 1-year postoperative mortality of 4.459, which was the third highest risk factor, after having 3 or more comorbidities or an ASA of 3 or 4. Monk TG et al. AnesthAnalg. 2005;100:4-10.

11. Physiologic Changes with Aging • Functional and structural changes occur in most organ systems • Although the basal function may remain stable in various organs systems, the functional reserve and the ability to compensate under physiologic stress are greatly reduced

12. Physiologic Changes with Aging: Body composition • Skeletal muscle mass decreased • Percentage of body fat increased • Total body water decreased • Water-soluble drugs: reduced volume of distribution • Lipid-soluble drugs: increased volume of distribution • DO2 and heat production decreased

13. Physiologic Changes with Aging:Central nervous system • Brain mass decreases, mainly from loss of neural tissue • 10%20% reduction in cerebral blood flow • Decreased number of serotonin, acetylcholine, and dopamine receptors • Decline in memory, reasoning, perception • Disturbed sleep/wake cycle

14. Physiologic Changes with Aging:Cardiovascular system • LV hypertrophy and decreased compliance • Increase in vascular rigidity • Decreased compliance of venous vessels • Desensitization of β-adrenergic receptors • Decreased PNS tone and increased SNS tone • SVR and SBP increased • SV and CO decreased • Diastolic LV dysfunction • Decreased maximally attainable HR

15. Physiologic Changes with Aging:Pulmonary system • ↑ Central airway size and ↓ small airway diameter  no change in airway resistance • ↓ Functional alveolar surface area • ↓ Gas exchange  ↓ PaO2 and ↑ Aa gradient • ↑ Lung compliance and RV leads to ↑ FRC • No changes in TLC • Result is ↑ RV/TLC and FRC/TLC ratios

16. Increase PHYSIOLOGIC CHANGES WITH AGING:PULMONARY SYSTEM Decrease Respiratory muscle strength Chest wall height Respiratory center sensitivity Chest wall compliance Effective cough and swallow  ↑ aspiration risk DLCO2 PIMAX and PEMAX ERV and VC FVC, FEV1, FEV1/VC, and FEF at low lung volumes Chest wall stiffness AP diameter Closing volume and closing capacity

17. Physiologic Changes with Aging:Renal system • Tissue mass decreased • Perfusion decreased • GFR decreased • Reduced ability to dilute and concentrate urine and conserve sodium • Drug clearance decreased

18. Physiologic Changes with Aging:Hepatic system • Tissue mass decreased • Blood flow decreased • Possible decrease in affinity for substrate • Possible decrease in intrinsic activity • Decreased first-pass metabolism of some drugs

19. Physiologic Changes with Aging: Endocrine changes • ↓ ADH response to hypovolemia and hypotension • ↓ Renin and aldosterone leads to ↓ response to sodium restriction and postural changes are blunted • No changes in adrenocorticotropic hormone, cortisol, catecholamine production in adrenal medulla, or TSH • Insulin release is impaired • Impaired peripheral tissue resistance and decreased clearance leads to ↑ plasma insulin levels and ↑ fat deposits

20. Physiologic Changes with Aging:PK And PD issues • Protein binding • ↓ Level of proteins • Multiple medications interfere with drug binding sites • ↑ Level of free unbound drug in plasma  prolonged effect • ↓ Lean and ↑ fat body mass • ↑ Storage of lipid-soluble drugs  prolonged effect and longer time for elimination • ↓ Circulating blood volume • ↑ Initial plasma drug concentration

21. Conclusions • The proportion of older individuals in the US population continues to rise • Many of them will require surgery and anesthesia • Physiologic changes of age have a great impact in the perioperative period

22. Acknowledgments • Supported by a grant from the Geriatric Education for Specialty Residents Program (GS), which is administered by the American Geriatrics Society and funded by the John A. Hartford Foundation of New York City • Our gratitude to Dr. Alec Rooke for his assistance with many of these slides

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